Clamping devices of this kind are known from DE 200 03 729 U1. In these clamping devices, retention of a draw-in bolt in the receptacle of the clamping device is accomplished here by way of a collet chuck that has multiple resilient clamping tongues which at one of their end regions are retained on an annular element held in the receptacle, and in the region of their free ends are movable with elastic deformation between a radially inner clamping position and a radially outer release position. Provided for actuation of the clamping mechanism is a piston that is pressed by a spring packet into a lower closed position in which the clamping tongues are pressed radially inward into their clamping position, and that is movable hydraulically into an upper release position in which it releases the clamping tongues so that the latter can deflect radially outward.
The clamping mechanism furthermore possesses a hydraulically or pneumatically actuable opening piston that is in engagement with the clamping tongues on the inner side in such a way that the free ends of the clamping tongues can be spread out into the release position by an axial motion of the opening piston, and the draw-in bolt can thus be removed from the receptacle or inserted thereinto.
The known clamping mechanism has proven entirely successful in practical use. It is nevertheless regarded as disadvantageous in that it possesses a relatively complex configuration. Another criticism occasionally expressed is that the clamping device is cumbersome to handle, since the draw-in bolt must be positioned exactly in the clamping device so that the clamping mechanism operates reliably.